Catheters for infusion of cardiovascular fluids into blood are disclosed. The cardiovascular fluid may, for example, comprise water highly supersaturated with a gas such as oxygen. Each catheter comprises one or more capillary tubings (or capillaries) through which a cardiovascular fluid flows. The distal end of each capillary is mounted (e.g., potted) preferably flush with an external surface of a catheter sidewall, while the proximal end of each capillary is in fluid communication with a cardiovascular fluid flowing through the lumen of the catheter. The combination of the catheter shape and the orientation of the distal end of each capillary relative to the longitudinal axis of the catheter provides control over the mixing pattern of the cardiovascular fluid with blood flowing within a vascular space such as an aorta.